Rockbox v3.0 final released just today (the 23rd of September) after more than 3 years since previous stable build.
http://download.rockbox.org/release/3.0/ (contains the main Rockbox program along with fonts and manuals for the program)
read more about it here... http://www.rockbox.org/
Apple: 1st through 5.5th generation iPod, iPod Mini and 1st generation iPod Nano
(not the Shuffle, 2nd/3rd gen Nano, Classic or Touch)
Archos: Jukebox 5000, 6000, Studio, Recorder, FM Recorder, Recorder V2 and Ondio
Cowon: iAudio X5, X5V, X5L, M5, M5L, M3 and M3L
iriver: H100, H300 and H10 series
Olympus: M:Robe 100
SanDisk: Sansa c200, e200 and e200R series (not the v2 models)
Toshiba: Gigabeat X and F series (not the S series)
it basically supports alot more audio formats then stock firmware does in general and allows for much more customization over stock firmware etc etc... the reason i bought my Sansa was so that i could run Rockbox which i accidentally discovered
p.s. been running Rockbox for a while now and it's much better than stock firmware on my Sandisk Sansa e250 (2GB) player.... and it takes less than 5minutes to install and get up and running once you know what to do on my particular player.... the e200r series (i.e. the Rhapsody ones) are a little harder to install rockbox to (i did it on my cousins) than the e200 ones but it still works just as good once it's up and running.